As electrophotographic photosensitive members to be mounted to electrophotographic apparatus, development is energetically made on organic electrophotographic photosensitive members (hereinafter also “electrophotographic photosensitive member(s)”) containing organic photoconductive materials. Also, at present, the organic electrophotographic photosensitive members are prevalent as electrophotographic photosensitive members used in electrophotographic process cartridges or electrophotographic apparatus, and are manufactured in a large scale. Of the organic electrophotographic photosensitive members, multi-layer type electrophotographic photosensitive members are in a large usage. In such multi-layer type electrophotographic photosensitive members, functions necessary for an electrophotographic photosensitive member are functionally separated into individual layers so as to be improved in characteristic features.
As a method for producing the multi-layer type electrophotographic photosensitive members, a method is commonly known in which functional materials are dissolved in organic solvents to prepare coating fluids, which are then multiply coated on a support. Of the individual layers of the multi-layer type electrophotographic photosensitive members, a charge transporting layer is required in many cases to have durability, and hence a coat therefor may have a larger layer thickness when compared with other layers. Hence, a coating fluid therefor is used in a large quantity, so that the layer formed may be one formed using an organic solvent in a large quantity.
In order to reduce the quantity of organic solvents to be used in producing electrophotographic photosensitive members, it is desirable to reduce the quantity of an organic solvent to be used in a charge transporting layer coating fluid. However, in order to prepare such a charge transporting layer coating fluid, a halogenous solvent or aromatic organic solvent must be used because charge transporting materials and binder resins have a high solubility in such solvents, and it has been difficult to reduce the quantity of organic solvents to be used.
PTL (Patent Literature) 1 reports an effort at aiming to reduce the quantity of organic solvents in coating materials for forming charge transporting layers, for the purpose of cutting down volatile substances or reducing carbon dioxide. This publication discloses that an organic solution prepared by dissolving in an organic solvent the substances to be contained in the charge transporting layer is formed into oil droplets in water to prepare an emulsion type coating fluid.